Display control program, display control apparatus, display control method, and recording medium

ABSTRACT

There is provided a display control program for a computer. The display control program includes: by an image generation block, setting a viewpoint position and a sightline direction in accordance with one of a position and an attitude of a head mounted display worn on the head of a user and rendering an object arranged in a virtual three-dimensional space so as to generate an image to be displayed on the head mounted display; and by a rotation control block, upon acquiring an instruction for rotating a game field arranged in the virtual three-dimensional space, rotating the game field around an axis perpendicular to the game field.

BACKGROUND

The present disclosure relates to a display control technology and, moreparticularly, to a display control program, a display control apparatus,and a display control method that are configured to control display on ahead mounted display, and a non-transitory computer-readable recordingmedium.

A game which is able to be played by a user wearing on his or her head ahead mounted display that is connected to a game machine and operating acontroller for example while looking at a screen displayed on the headmounted display has been popular. With an ordinary stationary displayconnected to a game machine, the user's visual field range extends alsoto the outside of a display screen, so that the user may not concentrateon the screen or lose the sense of immersion in the game being played.On the contrary, wearing a head mounted display provides effects of theincreased sense of immersion in the video world and enhanced gameentertainment.

SUMMARY

In causing a head mounted display to display a virtual three-dimensionalspace, a position farther from a viewpoint position is lower invisibility than a position nearer to the viewpoint position. The presentdisclosure was made in consideration of this phenomenon. Therefore, itis desirable to provide a technique of enhancing the visibility of animage that is displayed on a head mounted display.

In carrying out the disclosure and according to one mode thereof, thereis provided a display control program for a computer, including: by animage generation block, setting a viewpoint position and a sightlinedirection in accordance with one of a position and an attitude of a headmounted display worn on the head of a user head and rendering an objectarranged in a virtual three-dimensional space so as to generate an imageto be displayed on the head mounted display; and by a rotation controlblock, upon acquiring an instruction for rotating a game field arrangedin the virtual three-dimensional space, rotating the game field aroundan axis perpendicular to the game field.

According to another mode thereof, there is provided a display controlapparatus including: an image generation block configured to set aviewpoint position and a sightline direction in accordance with one of aposition and a direction of a head mounted display worn on the head of auser head and render an object arranged in a virtual three-dimensionalspace so as to generate an image to be displayed on the head mounteddisplay; and a rotation control block configured, upon acquiring aninstruction for rotating a game field arranged in the virtualthree-dimensional space, to rotate the game field around an axisperpendicular to the game field.

According to a further mode thereof, there is provided a display controlmethod for a computer, including: setting a viewpoint position and asightline direction in accordance with one of a position and a directionof a head mounted display worn on the head of a user head and renderingan object arranged in a virtual three-dimensional space so as togenerate an image to be displayed on the head mounted display; androtating, upon acquiring an instruction for rotating a game fieldarranged in the virtual three-dimensional space, the game field aroundan axis perpendicular to the game field.

According to a still further mode thereof, there is provided anon-transitory computer-readable recording medium recording a program,the program including: by an image generation block, setting a viewpointposition and a sightline direction in accordance with one of a positionand an attitude of a head mounted display worn on the head of a userhead and rendering an object arranged in a virtual three-dimensionalspace so as to generate an image to be displayed on the head mounteddisplay; and by a rotation control block, upon acquiring an instructionfor rotating a game field arranged in the virtual three-dimensionalspace, rotating the game field around an axis perpendicular to the gamefield.

According to the present disclosure, a technique of enhancing thevisibility of an image that is displayed on a head mounted display isprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective views illustrating a usage environment of a gamesystem practiced as one embodiment of the present disclosure.

FIG. 2 is an external perspective view illustrating a head mounteddisplay practiced as one embodiment of the present disclosure.

FIG. 3 is a functional configuration diagram illustrating the headmounted display.

FIGS. 4A and 4B are diagrams illustrating external views of an inputapparatus.

FIG. 5 is a diagram illustrating a configuration of a game apparatus.

FIG. 6 is a functional configuration diagram illustrating the gameapparatus.

FIG. 7 is a diagram illustrating an example of a game screen that isdisplayed on a display apparatus of the head mounted display.

FIG. 8 is a diagram illustrating another example of a game screen thatis displayed on the display apparatus of the head mounted display.

FIG. 9 is a diagram illustrating still another example of a game screenthat is displayed on the display apparatus of the head mounted display.

FIG. 10 is a diagram illustrating yet another example of a game screenthat is displayed on the display apparatus of the head mounted display.

FIG. 11 is a diagram illustrating a different example of a game screenthat is displayed on the display apparatus of the head mounted display.

FIG. 12 is a diagram illustrating a still different example of a gamescreen that is displayed on the display apparatus of the head mounteddisplay.

FIG. 13 is a flowchart indicative of a procedure of a game controlmethod practiced as one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In present embodiments, the following describes a display technologybased on a head mounted display (HMD). A head mounted display is adisplay apparatus that is mounted on the head of a user such that theeyes of the user are covered, thereby allowing the user to view stillimages and moving images displayed on a display screen arranged in frontof the user's eyes. The subjects to be displayed on the head mounteddisplay may be such content as movies or television programs; in thepresent embodiment, an example is described in which a head mounteddisplay is used as a display apparatus that displays game images.

A game apparatus practiced according to the present embodiment is oneexample of a display control apparatus of the present disclosure. Thegame apparatus generates a game image including a game field anddisplays the generated game image on a head mounted display by arrangingthe game field on a table arranged in a virtual three-dimensional space,setting a viewpoint position above the game field, and rendering thevirtual three-dimensional space. This setup allows a user to continueplaying a game while understanding the situations of the game field bylooking over the game field. With the game field arranged on the table,it is easier for the user to visually recognize a situation on the frontside near the viewpoint position of the user, but it is difficult forthe user to visually recognize a situation on the depth side far fromthe viewpoint position of the user. Therefore, in the presentembodiment, a function is provided to the user that rotates a table onwhich a game field is arranged around the perpendicular axis.Consequently, if the user wants to attentively view the situation on thegame field on the depth side, the user is able to move the position ofattention to the front side near the viewpoint position of the user byrotating the table, so that the user is able to easily visuallyrecognize the entire game field by rotating the game field depending onthe situation. As a result, the convenience of the user is enhanced.

Now, referring to FIG. 1, there is shown an environment in which a gamesystem 1 practiced as one embodiment of the present disclosure is used.The game system 1 includes a game apparatus 10 for executing a gameprogram, an input apparatus 6 through which user instructions areentered in the game apparatus 10, an imaging apparatus 14 for takingpictures of a real space around a user, a head mounted display 100 fordisplaying a first game image generated by the game apparatus 10, and adisplay apparatus 12 for displaying a second game image generated by thegame apparatus 10.

The game apparatus 10 executes a game program on the basis ofinstruction input entered from the input apparatus 6 or the head mounteddisplay 100 and the position or attitude of the input apparatus 6 or thehead mounted display 100, and generates a first game image to transmitthe generated first game image to the head mounted display 100 andgenerates a second game image to transmit the generated second image tothe display apparatus 12.

The head mounted display 100 displays the first game image generated inthe game apparatus 10. Further, the head mounted display 100 transmitsinformation related with a user input operation done through an inputapparatus arranged on the head mounted display 100 to the game apparatus10. The head mounted display 100 may be connected to the game apparatus10 with a wired cable or in a wireless manner such as wireless localarea network (LAN).

The display apparatus 12 displays the second game image generated in thegame apparatus 10. The display apparatus 12 may be a television having adisplay and a speaker or a computer display.

The input apparatus 6 has a function of transmitting a user instructioninput to the game apparatus 10; in the present embodiment, the inputapparatus 6 is configured as a wireless controller that provideswireless communication with the game apparatus 10. The input apparatus 6and the game apparatus 10 may establish wireless connection by use of aBluetooth (trademark) protocol. It should be noted that the inputapparatus 6 may also be a wired controller connected to the gameapparatus 10 with a cable, in addition to a wireless controller.

The input apparatus 6, driven by a battery, is configured by having twoor more buttons for performing instruction input operations for making agame progress. When the user operates a button of the input apparatus 6,an instruction input done by this operation is transmitted to the gameapparatus 10 through wireless communication.

The imaging apparatus 14 is a video camera configured by a chargecoupled device (CCD) imaging device or a complementary metal-oxidesemiconductor (CMOS) imaging device for example and takes pictures of areal space with a predetermined period, thereby generating a frame imagefor each period. The imaging apparatus 14 is connected to the gameapparatus 10 through an interface such as universal serial bus (USB) orthe like. In image captured by the imaging apparatus 14 is used toderive the positions and attitudes of the input apparatus 6 and the headmounted display 100 in the game apparatus 10. The imaging apparatus 14may be a ranging camera for obtaining distance or a stereo camera. Inthis case, the imaging apparatus 14 allows the acquisition of distancesbetween the imaging apparatus 14 and the input apparatus 6 or the headmounted display 100 for example.

In the game system 1 of the present embodiment, the input apparatus 6and the head mounted display 100 each have a light emission block thatemits a light of two or more colors. During a game, the light emissionblock emits light in color indicated by the game apparatus 10 which isimaged by the imaging apparatus 14. The imaging apparatus 14 takes apicture of the input apparatus 6 and generates a frame image, supplyingthe generated frame image to the game apparatus 10. Acquiring the frameimage, the game apparatus 10 derives the positional information aboutthe light emission block in the real space from the position and size ofthe image of the light emission block in the frame image. The gameapparatus 10 handles the positional information as a game operationinstruction, thereby reflecting the game operation instruction onto suchprocessing of the game as controlling the operation of a player'scharacter.

In addition, the input apparatus 6 and the head mounted display 100 eachhas an acceleration sensor and a gyro sensor. The sensor detectionvalues are transmitted to the game apparatus 10 with a predeterminedperiod. Receiving the sensor detection values, the game apparatus 10acquires the attitude information of the input apparatus 6 and the headmounted display 100 in the real space. The game apparatus 10 handles theattitude information as an operation instruction for a game and reflectsthe attitude information onto the processing of the game.

It should be noted that, if a game is executed only by a user who wearsthe head mounted display 100, the display apparatus 12 may not beprovided and the second game image to be displayed on the displayapparatus 12 may not be generated. Further, if the positionalinformation of the input apparatus 6 and the head mounted display 100 ismeasured by acceleration sensors built in the input apparatus 6 and thehead mounted display 100, then the imaging apparatus 14 may not beprovided.

Referring to FIG. 2, there is shown an external view of the head mounteddisplay 100 practiced as one embodiment of the present disclosure. Thehead mounted display 100 has a main body section 110, a head contactsection 112, and a light emission section 114.

Arranged on the main body section 110 are a display, a globalpositioning system (GPS) unit for acquiring positional information, anattitude sensor, and a communication apparatus. The head contact section112 may include a biometric information acquisition sensor for detectingbiometric information such as user's body temperature, heartbeat, bloodcomposition, perspiration, brainwave, and brain blood flow. The lightemission selection 114 emits light in a color indicated by the gameapparatus 10 as described above and functions as the standard forcomputing the position of the head mounted display 100 in an image takenby the imaging apparatus 14.

The head mounted display 100 may further include a camera for takingpictures of user's eyes. The camera arranged on the head mounted display100 allows detection of field of view, pupil movement, and blink of theeyes of the user.

In the present embodiment, the head mounted display 100 is described;however, the display control technology of the present embodiment isalso applicable not only to the head mounted display 100 in a limitedsense but also a head mounted display having eye glasses, aspectacle-type display, a spectacle-type camera, a headphone, a headset(a headphone with a microphone), an earphone, an earring, an ear-hookedcamera, a hat, a hat with camera, or a hair band, for example.

Referring to FIG. 3, there is shown a functional diagram of the headmounted display 100. The head mounted display 100 has an input interface122, an output interface 130, a backlight 132, a communication controlblock 140, a network adaptor 142, an antenna 144, a storage block 150, aGPS unit 161, a wireless unit 162, an attitude sensor 164, an externalinput/output terminal interface 170, an external memory 172, a clockblock 180, a display apparatus 190, and a control block 160. Thesefunctional blocks are also realized by only hardware, only software, ora combination thereof.

The control block 160 is a main processor that processes signals such asan image signal and a sensor signal, instructions, and data and outputsthe results of the processing. The input interface 122 receives anoperation signal and a setting signal from an input button or the likeand supplies the received signals to the control block 160. The outputinterface 130 receives an image signal from the control block 160 andmakes the display apparatus 190 display the received image signal. Thebacklight 132 supplies backlight to a liquid crystal display that makesup the display apparatus 190.

The communication control block 140 transmits data entered from thecontrol block 160 to the outside in a wired or wireless manner throughthe network adaptor 142 or the antenna 144. Also, the communicationcontrol block 140 receives data from the outside in a wired or wirelessmanner through the network adaptor 142 or the antenna 144 and outputsthe received data to the control block 160.

The storage block 150 temporarily stores data, parameters, and operationsignals that are processed by the control block 160.

The GPS unit 161 receives positional information from a GPS satellite byfollowing an operation signal from the control block 160 and suppliesthe received positional information to the control block 160. Thewireless unit 162 receives positional information from a wireless basestation by following an operation signal from the control block 160 andsupplies the received positional information to the control block 160.

The attitude sensor 164 detects attitude information such as thedirection and tilt of the main body section 110 of the head mounteddisplay 100. The attitude sensor 164 can be realized by appropriatelycombining a gyro sensor, an acceleration sensor, and an angularacceleration sensor.

The external input/output terminal interface 170 is an interface for theconnection of peripheral devices such as a USB controller. The externalmemory 172 is an external memory such as a flash memory.

The clock block 180 sets time information on the basis of a settingsignal received from the control block 160 and supplies time data to thecontrol block 160.

Referring to FIG. 4, there is shown an external view of the inputapparatus 6. FIG. 4A shows an external configuration of the top view ofthe input apparatus 6. The user holds a left-side hold section 78 b bythe left hand and a right-side hold section 78 a by the right hand andoperates the input apparatus 6. Arranged on top of the housing of theinput apparatus 6 are a direction key 71, analog sticks 77 a and 77 band four-types of operation buttons 76 that make up the input block.Four-types of buttons 72 through 75 are identified by different colorsand different symbols. Namely, the circle button 72 has a red circle,the cross button 73 has a blue cross, the square button 74 has a purplesquare, and a triangle button 75 has a green triangle. On top of thehousing, a touch pad 79 is arranged on a flat area between the directionkey 71 and the operation button 76. The touch pad 79 sinks when the userpresses the panel and returns to the original position when the userreleases the panel, thus functioning also as a press button.

A function button 80 is arranged between the two analog sticks 77 a and77 b. The function button 80 is used to power on the input apparatus 6and, at the same time, activate the communication function ofinterconnecting the input apparatus 6 and the game apparatus 10. Afterconnection of the input apparatus 6 with the game apparatus 10, thefunction button 80 is also used to display a menu screen on the gameapparatus 10.

A SHARE button 81 is arranged between the touch pad 79 and the directionkey 71. The SHARE button 81 is used to enter a user instruction for anoperating system (OS) or the system software of the game apparatus 10.An OPTIONS button 82 is arranged between the touch pad 79 and theoperation button 76. The OPTIONS button 82 is used to enter a userinstruction for an application (a game) that is executed on the gameapparatus 10. The SHARE button 81 and the OPTIONS button 82 may beformed as push buttons.

FIG. 4B shows an external configuration of a side of the rear section ofthe input apparatus 6. On top of the side of the rear section of thehousing of the input apparatus 6, the touch pad 79 extends from the topof the housing; below the side of the rear section of the housing, alight-emitting block 85 that is long sideways is arranged. Thelight-emitting block 85 has red (R), green (G), and blue (B) lightemitting diodes (LEDs) that are turned on according to emitted lightcolor information transmitted from the game apparatus 10.

On the side of the rear section of the housing, an upper button 83 a andan upper button 83 b are arranged symmetrically along longitudinaldirection, and a lower button 84 a and a lower button 84 b are arrangedsymmetrically along longitudinal direction. The upper button 83 a andthe lower button 84 a are operated by the index finger and the middlefinger of the right hand of the user, respectively; the upper button 83b and the lower button 84 b are operated by the index finger and themiddle finger of the left hand of the user, respectively. As shown,arranging the light-emitting block 85 between the line of the upperbutton 83 a and the lower button 84 a of the right side and the line ofthe upper button 83 b and the lower button 84 b of the left side makesthe light-emitting block 85 visible without being hidden by the indexfinger or the middle finger that operates these buttons, therebyallowing the imaging apparatus 14 to suitably image the turned-onlight-emitting block 85. The upper buttons 83 a and 83 b may beconfigured as a push button and the lower buttons 84 a and 84 b may beconfigured as a pivotally supported trigger button.

Referring to FIG. 5, there is shown a configuration of the gameapparatus 10. The game apparatus 10 has a main power supply button 20, apower supply ON LED 21, a standby LED 22, a system controller 24, aclock 26, a device controller 30, a media drive 32, a USB module 34, aflash memory 36, a wireless communication module 38, a wiredcommunication module 40, a sub system 50, and a main system 60.

The main system 60 has a main central processing unit (CPU), a memoryand a memory controller that form a main storage unit, and a graphicsprocessing unit (GPU) and so forth. The GPU is mainly used forcomputational processing of game programs. These functions areconfigured as system-on-chips which may be formed on a single chip. Themain CPU has a function of executing game programs recorded to anauxiliary storage apparatus 2.

The sub system 50 has a sub CPU and a memory and a memory controllerthat form a main storage apparatus and so forth, but does not haveeither a GPU or a function of executing game programs. The number ofcircuit gates of the sub CPU is lower than the number of circuit gatesof the main CPU and the operation power dissipation of the sub CPU islower than that of the main CPU. The sub CPU also operates while themain CPU is in a standby state and the processing function of the subCPU is restricted to lower the power dissipation.

The main power supply button 20 that is arranged on the front side ofthe housing of the game apparatus 10 and is an input block through whichuser operation input is executed, is operated to power on/off the mainsystem 60 of the game apparatus 10. The power supply ON LED 21 is turnedon when the main power supply button 20 is turned on and the standby LED22 is turned on when the main power supply button 20 is turned off.

The system controller 24 detects the pressing of the main power supplybutton 20 by the user. When the main power supply button 20 is pressedwith the main power supply being off, the system controller 24 acquiresthis pressing operation as “on instruction,” while, when the main powersupply button 20 is pressed with the main power supply being on, thesystem controller 24 acquires this pressing operation as “offinstruction.”

The clock 26 is a realtime clock that generates current date and timeinformation and supplies the generated current date and time informationto the system controller 24, the sub system 50, and the main system 60.

The device controller 30 is configured as a large-scale integrated (LSI)circuit that executes transfer of information between devices like asouth bridge. As shown, the device controller 30 is connected to devicessuch as the system controller 24, the media drive 32, the USB module 34,the flash memory 36, the wireless communication module 38, the wiredcommunication module 40, the sub system 50, and the main system 60. Thedevice controller 30 absorbs the difference in electric properties anddata transfer speeds between the devices and controls the timing of datatransfer.

The media drive 32 is a drive apparatus which is loaded with a read onlymemory (ROM) medium 44 recording application software such as games andlicense information to drive the ROM medium 44, thereby reading programsand data from the ROM medium 44. The ROM medium 44 is a read-onlyrecording medium such as an optical disc, a magneto-optical disc, or aBlu-ray disc, for example.

The USB module 34 is a module for providing connection with externaldevices through a USB cable. The USB module 34 may provide connection tothe auxiliary storage apparatus 2 and the imaging apparatus 14 through aUSB cable. The flash memory 36 is an auxiliary storage apparatus thatconfigures an internal storage. The wireless communication module 38provides wireless communication with the input apparatus 6 for exampleon the basis of a communication protocol such as Bluetooth (trademark)protocol or the Institute of Electrical and Electronic Engineers (IEEE)802.11 protocol. It should be noted that the wireless communicationmodule 38 may be compliant with the third-generation digital mobilephone scheme based on the international mobile telecommunication 2000(IMT-2000) specified by the International Telecommunication Union (ITU)or, further, may be compliant with digital mobile phone schemes of othergenerations. The wired communication module 40 provides wiredcommunication with external devices, an external network via AP8 forexample.

Referring to FIG. 6, there is shown a functional configuration of thegame apparatus 10. The main system 60 of the game apparatus 10 has acontrol portion 310 and a data hold portion 360. The control portion 310has a game control block 311, an instruction input acquisition block312, a rotation control block 313, a direction information display block314, and an image generation block 315.

The data hold portion 360 holds program data of games that are executedon the game apparatus 10 and various kinds of data that are used by gameprograms.

The instruction input acquisition block 312 acquires, from the inputapparatus 6 or the head mounted display 100, information associated withuser instruction input accepted by the input apparatus 6 or the headmounted display 100. The game control block 311 executes a game programso as to make the game progress on the basis of a user's instructioninput acquired by the instruction input acquisition block 312.

The image generation block 315 sets a viewpoint position and a sightlinedirection in accordance with the position and attitude of the headmounted display 100 and renders an object arranged in a virtualthree-dimensional space, thereby generating an image to be displayed onthe head mounted display 100. The image generation block 315 moves theviewpoint position in match with the position of the head mounteddisplay 100, namely, the movement of the position of the head of theuser so as to change sightline direction in match with the direction ofthe head mounted display 100, namely, the direction in which the head ofthe user is directed. This setup allows the generation of a game imagethat gives an effect that the user were actually inside a virtualthree-dimensional space.

The rotation control block 313 acquires an instruction for rotating agame field arranged in a virtual three-dimensional space and thenrotates the game field around the axis that is perpendicular to the gamefield. The direction information display block 314 displays, on the headmounted display 100, direction information for notifying a user of thedirection in which to direct the head mounted display 100. The followingdescribes features of these configurations with reference to gamescreens.

Now, referring to FIG. 7, there is shown one example of a game screenthat is displayed on the display apparatus 190 of the head mounteddisplay 100. In the game screen, an image internal to a room built as avirtual three-dimensional space is displayed. In this room, a table 520and a Satan 522 are arranged. On top of the table 520, a game field 500is arranged. In this game, a devil 512 is arranged in the game field 500so as to be grown up, the devil 512 is made fight a warrior 514 invadingfrom a castle 504 so as to block the invasion of the warrior 514,thereby protecting the Satan 522 residing in a tower 502 against thewarrior 514. The room displayed in the game screen is the room of theSatan 522 on top of the tower 502. While correctly understanding thesituation of the game field 500 and getting advice of the Satan 522 forexample, the user plots a strategy such as the type of a devil to bearranged, the timing of the arrangement, arrangement positions, and thelike, thereby arranging the devil in the game field 500. If the devilarranged in the game field 500 cannot prevent the invasion by thewarrior 514, letting the warrior 514 into the tower 502, a state inwhich the warrior 514 invades the room to take away the Satan 522 isshown, upon which the game is over. If the devil can prevent theinvasion by the warrior 514 within a predetermined period of time orwithin the predetermined number of times, the game is cleared.

The game control block 311 has a function of a movement control blockfor controlling the movement of the warrior 514 that is one example of afirst object movable in the game field 500, thereby making the warrior514 go out of the castle 504 with predetermined timings so as to movethe warrior 514 along a road 516 to the tower 502. The game controlblock 311 controls the activities of the warrior 514 and a devil 510 anddevil 512 arranged in the game field 500 by the user and, when thewarrior 514 encounters the devil 510 or the devil 512, makes both fighteach other, thereby deleting the loser from the game field 500. Alsoarranged in the game field 500 are a tree 506 and a flower 508 that areexamples of second objects that are not controlled in movement by thegame control block 311 functioning as the movement control block.

A prey-predator relationship is set to the devils that can be arrangedin the game field 500; for example, the devil 510 grows up by eating theflower 508 and the devil 512 grows up by eating the devil 510. The userarranges the devils in the game field 500 by also considering theprey-predator relationship of the devils and nurtures the devils.

In a game screen that is shown at the start of a game, the direction ofthe game field 500 is set such that the tower 502 that is an ownterritory is on the front side near the viewpoint position of the userand the castle 504 that is an enemy territory is on the depth side farfrom the viewpoint position. If the user wants to check a situationaround the castle 504, the viewpoint position is moved in accordancewith the position of the head mounted display 100, so that it isnecessary for the user to approach a game field on the depth side of thetable 520 by moving the head forward by stretching the body or standingup and moving forward with the whole body; however, since it isdifficult for the user to visually recognize the surrounding situationin the real world while wearing the head mounted display 100, it is alsodifficult for the user to largely move around in the real world.Therefore, in the present embodiment, a function of rotating the gamefield 500 is provided to the user. This setup allows the user to rotatethe game field 500 such that a position to be visually recognized comestoward the user, so that the user can easily visually recognize theentirety of the game field 500 even if the user does not largely movearound the real world.

Referring to FIG. 8, there is shown another example of a game screenthat is displayed on the display apparatus 190 of the head mounteddisplay 100. The function of rotating the game field 500 is allocated tothe upper buttons 83 a and 83 b of the input apparatus 6. When the userclicks the upper button 83 a or 83 b, the rotation control block 313rotates the game field 500 by 90 degrees around the perpendicular axisthat is parallel to the up down direction in the virtualthree-dimensional space and passes the center of the game field 500. Thegame screen shown in FIG. 8 is a game screen obtained by rotating thegame field 500 by 90 degrees clockwise from the game screen shown inFIG. 7.

After rotating the game field 500, among the objects arranged in thegame field 500, the rotation control block 313 makes such second objectsas the tree 506 and the flower 508 that are not controlled in movementby the game control block 311 jump. This setup allows the user to easilyrecognize the rotation of the game field 500 and, at the same time,gives a visual effect that the objects on the table 520 jump by theimpact of the rotation of the game field 500. After rotating the gamefield 500, the rotation control block 313 does not make such firstobjects as the devils 510 and 512 and the warrior 514 that arecontrolled in movement by the game control block 311 jump. Rotation ofthe game field 500 changes the display positions of the devils 510 and512 and the warrior 514; however, since the positions of these firstobjects are very important with respect to the characteristics of thegame, prevention of the jump after the rotation of the game field 500allows the user to easily recognize the positions of the first objects.In another example, the first objects may be highlighted after therotation of the game field 500 by flashing display or color or sizechanging, for example. In still another example, the first objects maybe made jump after the rotation of the game field 500 and the secondobjects may not be made jump. This setup also allows the user to easilyrecognize the positions of the first objects after the rotation of thegame field 500. The tower 502 and the castle 504 may be made jump afterthe rotation of the game field 500 or may not be made jump. Each objectmay be made jump or not in accordance with the size, weight, or thedegree of fixture to the game field 500 of the object concerned. Thejumping may be preset for each object.

Referring to FIG. 9, there is shown still another example of a gamescreen that is displayed on the display apparatus 190 of the headmounted display 100. The game screen shown in FIG. 9 is a game screenobtained when the user moves his or her head downward from the gamescreen shown in FIG. 7. As the head mounted display 100 moves downward,the image generation block 315 moves the viewpoint position downward.Therefore, the elevation angle between the viewpoint position in thegame screen shown in FIG. 9 and the planar surface of the game field 500is smaller than that in the game screen shown in FIG. 7. At this moment,the distance between the object toward the user in the game field 500and the viewpoint position becomes shorter, so that rotating the gamefield 500 increases the moving speed of the object on the screen,thereby making it more possible to cause the user feel dizziness.Therefore, in the present embodiment, the rotation control block 313determines a speed with which to rotate the game field 500 on the basisof an elevation angle of the viewpoint position relative to the gamefield 500. To be more specific, as the elevation angle of the viewpointposition relative to the game field 500 gets larger, the rotationcontrol block 313 slows down the speed with which to rotate the gamefield 500. This setup allows the mitigation of the occurrence of thedizziness caused by the rotation of the game field 500.

Referring to FIG. 10, there is shown yet another example of a gamescreen that is displayed on the display apparatus 190 of the headmounted display 100. The game screen shown in FIG. 10 is a game screenobtained when the user moves his or her head to the right side from thegame screen shown in FIG. 7. Here assume that an event be taking placein the tower 502 in a game controlled by the game control block 311. Inthe game screen shown in FIG. 10, the user is directing his or her headto the right side, so that the tower 502 in which an event is takingplace is positioned outside the screen, namely, is not displayed in thegame screen. At this moment, in order for the tower 502 to get insidethe game screen, the image generation block 315 may automatically changethe sightline direction to the left side; however, if the sightlinedirection is changed with the user's head being standstill, dizzinessmay be easily caused. Therefore, in the present embodiment, in order forthe user to turn the head to the left side on his or her own to look inthe direction of the tower 502, the direction information display block314 displays, on the display apparatus 190 of the head mounted display100, an arrow mark 540 that is one example of the direction informationfor notifying the user of the direction in which to direct the headmounted display 100. This setup alerts the user to look in the leftdirection, so that the sightline direction of the user can be changed soas to display a position or an object to watch onto the game screen.

Referring to FIG. 11, there is shown a different example of a gamescreen that is displayed on the display apparatus 190 of the headmounted display 100. The game screen shown in FIG. 11 is a game screenobtained when the user moves his or her head to the left side from thegame screen shown in FIG. 10. When the user notices to direct the headto the left side and directs the head to the left, the tower 502 inwhich an event is taking place is displayed in the game screen. At thismoment, in order to notify the user that the object to currently watchis the tower 502, an effect line 542 is displayed around the tower 502so as to highlight the tower 502. Thus, if a subject to watch is notdisplayed in the game screen, it is necessary to display directioninformation for notifying the user to direct his or her head in thatdirection so as to display the subject to watch in the game screen;however, if a subject to watch is displayed in the game screen, thesubject to watch can be clearly indicated by highlighting the subject towatch on the game screen, so that the direction information may bedeleted from the game screen.

Not only in the case where, by changing the direction of the head of theuser, the direction of the head mounted display 100 is changed and thesightline direction for generating a game screen is changed accordingly,resulting in the change of the visual field of the game screen, but alsoin the case where the game field 500 is rotated, a subject to watchlocated outside the range of the game screen may be displayed in thegame screen. In this case too, the direction information display block314 may display direction information in the game screen if a subject towatch is not displayed in the game screen and delete directioninformation from the game screen if a subject to watch is displayed inthe game screen. Further, when a relative position between a subject towatch located outside the range of a game screen and the arrow mark 540displayed in the game screen has changed by changing the direction ofthe head mounted display 100 or rotating the game field 500, thedirection information display block 314 may change the direction of thearrow mark 540 displayed in the game screen to the direction of thesubject to watch.

Referring to FIG. 12, there is shown a still different example of a gamescreen that is displayed on the display apparatus 190 of the headmounted display 100. The game screen shown in FIG. 12 is a game screenobtained when the user moves his or her head to the right side from thegame screen shown in FIG. 7. A description 550 related with the game iswritten on a wall of the room not displayed in the game screen when theuser is directed forward in order to look at the game field 500.Generally, when the user looks at a so-called help screen such as this,a button allocated with a function of displaying the help screen isclicked to display the help screen on the game screen in a superimposedmanner or switch the game screen to the help screen. However, in thepresent embodiment, the help screen is arranged inside a virtualthree-dimensional space, so that, without damaging a world view of thegame that the user is located in the room of the Satan, the informationsuch as the help screen can be displayed, thereby further enhancing thesense of immersion in the game.

Referring to FIG. 13, there is shown a flowchart indicative of aprocedure of a game control method practiced as one embodiment of thepresent disclosure. When a game screen that includes a game fieldobtained by rendering a virtual three-dimensional space is displayed onthe head mounted display 100 and an instruction for rotating this gamefield is obtained from a user (S100), the rotation control block 313determines a rotational speed based on an elevation angle between aviewpoint position and the game field (S102) and rotates the game fieldat the determined rotational speed (S104). After rotating the gamefield, the rotation control block 313 makes an object not controlled inmovement jump, of the objects arranged in the game field (S106).

While preferred embodiments of the present disclosure have beendescribed using specific terms, such description is for illustrativepurpose only, and it is to be understood by those skilled in the artthat changes and variations may be made without departing from thespirit or scope of the following claims.

In the described embodiments of the disclosure, an example in which agame field of a game of tower defense type is rotated has beenexplained; however, subjects of rotation may be a game field of a roleplaying game, a game board of a board game, or a game screen of anygame. In addition, the technique described in the above-mentionedembodiments is applicable to displaying an image obtained by rendering avirtual three-dimensional space other than games onto a head mounteddisplay.

In the described embodiments of the disclosure, an example in which agame field is rotated around the axis perpendicular thereto has beenexplained. The axis perpendicular to a game field may be an axisparallel to the up down direction in the game field, an axisperpendicular to a plane surface included in a game field or the planesurface constituting a game field, or, if the game field is constitutedby a curved surface, an axis perpendicular to the tangent plane of thecurved surface. Also, the axis perpendicular to a game field may be anaxis that passes the center or gravity center of the game field or anaxis that passes a given position in a game field. In another example, asubject of rotation may be rotated around a horizontal axis parallel tothe left right direction in a virtual three-dimensional space. The pointis that a game field may be rotated such that a position fur from aviewpoint position comes to a position near the viewpoint position.Further, a game field may be moved or deformed such that a position furfrom a viewpoint position comes to a position near the viewpointposition by a method other than rotation.

The present technology contains subject matter related to that disclosedin Japanese Priority Patent Application JP 2016-175259 filed in theJapan Patent Office on Sep. 8, 2016, the entire content of which ishereby incorporated by reference.

What is claimed is:
 1. A non-transitory, computer readable storage medium containing a display control program, which when executed by a computer, causes the computer to carry out actions, comprising: setting a viewpoint position and a sightline direction in accordance with one of a position and an attitude of a head mounted display worn on the head of a user and rendering an object arranged in a virtual three-dimensional space so as to generate an image to be displayed on the head mounted display; acquiring an instruction, from a hand held controller, for rotating a game field arranged in the virtual three-dimensional space; and rotating the game field by 90 degrees around an axis perpendicular to the game field in response to a single button click.
 2. The non-transitory, computer readable storage medium according to claim 1, wherein the display control program causes the computer to further carry out actions, comprising: setting the viewpoint position above the game field so as to generate the image in which the game field is overlooked; and on the basis of an elevation angle of the viewpoint position relative to the game field, determining a speed at which to rotate the game field.
 3. The non-transitory, computer readable storage medium according to claim 2, wherein as the elevation angle of the viewpoint position relative to the game field gets smaller, the speed of the rotation of the game field is slowed down.
 4. The non-transitory, computer readable storage medium according to claim 1, wherein after rotating the game field, a display mode of the object arranged in the game field changes.
 5. The non-transitory, computer readable storage medium according to claim 4, the display control program causes the computer to further carry out actions, comprising: controlling a movement of a first object that is movable in the game field among objects arranged in the game field, wherein in changing the display mode of the object arranged in the game field after rotating the game field, a display mode of the first object is changed to a display mode of a second object that is not controlled in movement among objects arranged in the game field.
 6. The non-transitory, computer readable storage medium according to claim 1, the display control program causes the computer to further carry out actions, comprising displaying, on the head mounted display, direction information for notifying the user of a direction in which to direct the head mounted display.
 7. The non-transitory, computer readable storage medium according to claim 6, wherein if the object to be displayed is not displayed in the image generated direction information is displayed for notifying the direction in which to direct the head mounted display so as to display the object to be displayed.
 8. A display control apparatus comprising: an image generation block configured to set a viewpoint position and a sightline direction in accordance with one of a position and a direction of a head mounted display worn on the head of a user and render an object arranged in a virtual three-dimensional space so as to generate an image to be displayed on the head mounted display; and a rotation control block configured, upon acquiring an instruction, from a hand held controller, for rotating a game field arranged in the virtual three-dimensional space, to rotate the game field by 90 degrees around an axis perpendicular to the game field in response to a single button click.
 9. A display control method for a computer, comprising: setting a viewpoint position and a sightline direction in accordance with one of a position and a direction of a head mounted display worn on the head of a user and rendering an object arranged in a virtual three-dimensional space so as to generate an image to be displayed on the head mounted display; and rotating, upon acquiring an instruction, from a hand held controller, for rotating a game field arranged in the virtual three-dimensional space, the game field by 90 degrees around an axis perpendicular to the game field in response to a single button click.
 10. A non-transitory computer-readable recording medium recording a program, which when executed by a computer causes the computer to carry out actions, comprising: setting a viewpoint position and a sightline direction in accordance with one of a position and an attitude of a head mounted display worn on the head of a user and rendering an object arranged in a virtual three-dimensional space so as to generate an image to be displayed on the head mounted display; and upon acquiring an instruction, from a hand held controller, for rotating a game field arranged in the virtual three-dimensional space, rotating the game field by 90 degrees around an axis perpendicular to the game field in response to a single button click. 